The system seems stable, no lock ups or reboots, so I'm trying to determine if this is a defective CPU issue, in which case I need to RMA it with Amazon or AMD, or if this is something related to the BIOS settings. I've set everything to "normal" as far as overclocking goes. I've run a full memtest86+ on the memory to verify it's good.

I guess you flashed latest BIOS for your Crosshair VIII, anyway I advise you to open an Online Service Request | AMD and other ASUS request support to confirm possible faulty motherboard or CPU.

IMO Fedora offer an excellent distro support via Red Hat Bugzilla Main Page and if this bug appears in Problem Reporting app you can report it from your desktop, as you can see in bellow screenshots of my Fedora 32 Gnome desktop under ASRock B350 and Ryzen 3600

I can't remember if you must create a bugzilla account before report or is an option through the report process.

I've been doing Linux Systems Administration for 25 years and have run several AMD processors in the past and I honestly don't recall having ever seen an issue like this. I've looked over several of the threads on this site and seen this to be a common issue going back a while on the Ryzen line. Other than the MCE log entries, the system is extremely stable. I've already tried disabling the P-states in bios, per another thread, but the issue still exists. The machine has been rock solid other than these log entries, so it really has me baffled. I did open a ticket with AMD Global Support, but their reply was that they officially support Windows and I should test the system under Windows 10. I've not had a Windows computer at my house since the early 1990s! You are correct, I'm all flashed up to the latest BIOS and kernel. I did think about filing a bugzilla report, but held off as I first thought I had bad memory. I had installed 4 x DIMM for 64GB, and after running several passes of memtest86+ found one bad DIMM and did an RMA on that memory kit. The 32GB I'm running now tested good with an extended (i.e. overnight) memory test. I think I'll go ahead and open a bugzilla report now, as I don't think AMD will do an RMA with what I've provided them, log dumps and such. I'll update this thread if I ever come across a solution.

I did open a ticket with AMD Global Support, but their reply was that they officially support Windows and I should test the system under Windows 10. I've not had a Windows computer at my house since the early 1990s!

It seems that, unfortunately, there are things that haven't changed much since 1990. Really sad!

You are correct, I'm all flashed up to the latest BIOS and kernel. I did think about filing a bugzilla report, but held off as I first thought I had bad memory. I had installed 4 x DIMM for 64GB, and after running several passes of memtest86+ found one bad DIMM and did an RMA on that memory kit. The 32GB I'm running now tested good with an extended (i.e. overnight) memory test. I think I'll go ahead and open a bugzilla report now, as I don't think AMD will do an RMA with what I've provided them, log dumps and such.

AGESA ComboAM4 1.0.0.5 is officially out, I guess X570 users will be the first to enjoy latest BIOS with new code, may be AMD is aware of this issue and finally fix it via ASUS.